In cities across Turkey, political jingles, bunting and posters jostle for attention ahead of Sunday’s crucial general election, but one image overshadows them all. At 4,709 square meters, a gargantuan poster depicting President Recep Tayyip Erdoğan and Prime Minister Ahmet Davutoğlu has broken the Guinness World Record. The advertisement — described by the ruling Justice and Development Party (AKP) as a “surprise” for Erdoğan and Davutoğlu — is in step with the party’s fondness for competitively large projects, the most recent of which is the president’s €550 million palace in Ankara. Under the images of Davutoğlu and Erdoğan is a modest slogan: “The nation is enough for us.”

The poster was unveiled in Istanbul one week before the country goes to the polls, an auspicious sign of the AKP’s determination to hold center stage despite creeping support for the opposition. It is also a sign of the cult of personality that Erdoğan still enjoys. He ruled Turkey for 11 years as prime minister before becoming president last August, and is still considered the vote-winning, de facto leader of the AKP.

Erdoğan’s recent involvement in electoral scandal — despite his technically impartial status as head of state — has been met with international criticism. On Tuesday, he filed a criminal complaint against the editor of popular daily Cumhuriyet, demanding two life sentences for a news story he dubbed “treasonous.” On the same day, he sued the main opposition leader, Kemal Kiliçdaroğlu, for claiming that there are golden toilets in Erdoğan’s 1,150-room palace, demanding 33,560 euros in compensation for “mental anguish.”

The giant AKP poster — which is composed of thousands of photographs taken from social media — is also a sign of the party’s increasing control of public space. The AKP has been crowding the opposition out of the market by way of disproportional representation on state media, alleged cronyism, an army of social media trolls, and the repressive use of police and security laws to curb dissent.

Erdoğan’s stated plan to change the constitution to an executive presidential system is feared to be an indication that he is intent on creating a Central Asian-style dictatorship. The executive presidential system would grant him unprecedented power; the AKP’s performance on Sunday is expected to determine whether he can turn his plans into reality.

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Sunday’s election will be a make-or-break moment for Turkey; “a watershed moment,” says Sinan Ulgen, visiting scholar at Carnegie Europe and chair of the Turkish think-tank EDAM, but not just because they will decide Erdoğan’s future. According to Ulgen, this election is mostly about the balance of power between Erdoğan and the man he appointed as his successor, Prime Minister Ahmet Davutoğlu, and what this rivalry means for the future of the AKP.

This election is mostly about the balance of power between Erdoğan and the man he appointed as his successor, Prime Minister Ahmet Davutoğlu, and what this rivalry means for the future of the AKP.

“After June 7, Davutoğlu will become an elected prime minister as opposed to an appointed one, and he will use this to carve out greater political space for himself,” Ulgen says. “If the AKP wins a weak majority, Davutoğlu benefits, but if it wins a strong majority, it will be seen as an endorsement for Erdoğan’s presidency — it will show what he calls “the national will.”

Erdoğan’s push for an executive presidency could prove politically suicidal. Gareth Jenkins, senior associate fellow at the Joint Center’s Silk Road Turkey Initiative, views the approaching tussle for party leadership as a crucial stage in Erdoğan’s “long goodbye,” which he says began with the Gezi Park protests of 2013.

“Davutoğlu simply does not have the grassroots support that Erdoğan has,” adds Jenkins. “He has delusions of grandeur, of leading Turkey to new heights, but he will fail if he takes Erdoğan on. In the process, however, they will damage each other and there will be chaos and instability within the party. Neither will survive.”

Even if, come Sunday, the AKP does win the 330 seats needed to call a referendum on the new presidential system, current public support is low, and Ulgen is convinced that no referendum proposal could be sufficiently “sugar-coated” for the skeptical Turkish electorate to accept.

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With only untrustworthy polls to gauge public opinion in the run-up to the election, analysts are considering several possibilities for what the new government will look like, including coalition scenarios. The most significant unknown factor is the performance of the People’s Democratic Party (HDP), a leftist party with Kurdish roots. Turkey’s 15 million Kurds form the party’s core support base, but HDP co-chairs Selahattin Demirtaş and Figen Yüksekdağ are making a concerted effort to reach out to the wider electorate with a manifesto promising increased minority rights and greater local governance.

The most significant unknown factor is the performance of the People’s Democratic Party (HDP), a leftist party with Kurdish roots.

Should the HDP pass the 10 percent electoral threshold required to enter parliament, it will severely deplete the AKP’s majority. And if the AKP ends up with fewer than 276 seats, it may be forced into a coalition with one of the opposition parties, although all opposition leaders have vowed not to form any such coalition.

“Judging by the mood on the ground and the latest opinion polls, the chances of the HDP being in parliament seem high,” says Karabekir Akkoyunlu, assistant professor at the University of Graz’s Centre for Southeast European Studies, noting that the HDP’s base appears much more energized than the AKP base. “But opinion polls can be unreliable … and past predictions of the AKP’s imminent doom have turned out to be famously wrong.”

And even if polls predicting a strong opposition performance prove correct, the political situation would likely change soon after the vote. None of the viable coalition options would be likely to last beyond a year, which would result in new elections in 2016.

An alliance between the AKP and the secondary opposition party, the Nationalist Movement Party (MHP), is being hailed as the most likely coalition scenario, as the two parties share similar constituencies and are not as diametrically opposed as other pairings. Some have even floated the idea of a AKP-HDP coalition, a nightmare scenario for many Turkish voters who fear the HDP would be willing to support Erdoğan’s presidential plans in exchange for greater autonomy for Kurds, and possibly even the release of Abdullah Öcalan, the imprisoned leader of the Kurdistan Worker’s Party (PKK). HDP co-chair Demirtaş, however, has explicitly ruled out such a coalition, and it would hardly be palatable to Erdoğan.

A third scenario is possible in the event of a strong HDP performance and weaker-than-predicted AKP results: an opposition coalition of the MHP and the Republic People’s Party (CHP), the main opposition party, with temporary support from the HDP.

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Investors worried by coalition scenarios are hoping for a continuing AKP majority, says Isobel Finkel, Bloomberg’s Turkish banking reporter. “Investors are saying their best hopes for good governance lie in the sweet spot where the AKP have a strong enough majority to avoid coalition but not enough seats to change the constitution without the buy-in of other parties. Yet [electoral] uncertainty is why markets haven’t enjoyed their traditional pre-election rally: The lira’s still more than 10 percent down since the start of the year and the main stockmarket index is lower than it was a month ago,” says Finkel.

Ulgen argues that an AKP majority government would ultimately do more economic damage than good; conversely, a coalition government would initially be met with suspicion by international markets, but would prove a positive development for Turkey in the long-term by heralding democratic change.

One of the most unsettling possibilities is that Erdoğan will make use of his presidential right, so far unexercised in Turkish political history, to reject a proposed minority government. The president has the right to call for another election within 45 days, which could backfire for the AKP if the electorate becomes wary of the president’s unwarranted interference in the democratic process. But it could also lead to an increase in AKP votes from an electorate afraid of instability.

Coalition speculation assumes a victorious HDP, but many analysts predict the party will not pass the 10 percent threshold, allowing the AKP to comfortably retain its majority. Although the latest poll showed the HDP at an all-time high of 12 to 13 percent, fears remain that voters who currently claim they will vote tactically for the HDP to rob the AKP of seats are in fact harboring insurmountable suspicions of the party’s Kurdish separatist connections and will likely revert to one of the mainstream opposition parties at the ballot box. Co-chair Demirtaş has said his party remains “on a knife-edge.”

Should the HDP fail to pass the threshold, street violence and protests in Kurdish communities across the country are expected

Should the HDP fail to pass the threshold, street violence and protests in Kurdish communities across the country are expected to repeat the unrest which occurred during the siege of the Kurdish town of Kobane last October, when Demirtaş called people to the streets to protest against the government’s failure to help the besieged inhabitants. Twenty-one people died in the resulting clashes.

Unrest now seems more likely after the two explosions that killed at least two people and injured over one hundred at an HDP rally in Diyarbakir on Friday afternoon, generally understood to be a terrorist attack. However, Demirtaş called for calm and promised that “peace will win,” as riot police cleared the scene by blasting rally participants with water canon and tear gas.

Jenkins says that local “carnival-like” HDP campaigning has so successfully inspired its base in the southeast with the surety of success that a failure to pass the threshold will automatically be construed as electoral foul play. “There is no expectation of fair elections. Riots will occur as a kind of self-fulfilling prophecy,” says Jenkins.

Municipal elections last year were met with reports that stolen opposition ballots were replaced by pre-stamped AKP ballots in a coordinated operation aided by a mysterious nationwide blackout. Vote-rigging is alleged to have occurred in Ankara, where the incumbent AKP mayor Melih Gökçek retained his 20-year seat with a dubious 1 percent lead after the Supreme Electoral Board refused the opposition’s calls for a re-count. In contrast, the AKP successfully requested 15 recounts in the town of Ağrı, all of which they lost.

The more profound danger of the HDP’s failure to reach parliament will be its long-term political consequence. “If the HDP fail they will withdraw from [mainstream politics in] Ankara and retreat to their original power base in Diyarbakır,” says Jenkins. Since 2011, the Kurdish region of Diyarbakır in the southeast has been effectively run by a local form of government dominated by the PKK and referred to as “a local democracy for the south east” — the natural plan B for the HDP if it fails to get into parliament.

Most analysts agree that the crucial issue is to keep the HDP within mainstream politics and away from PKK domination, the opposite outcome is widely viewed as a disaster for Turkey’s long-term internal stability. With expectations of vote-rigging at an all-time high, however, it is a very real fear.

As polling day approaches, worries remain that all will not go smoothly, despite the Interior Ministry’s assurances that extra security measures — including armored vehicles and 150,000 police — have been arranged. A suspicious Turkish public has decided to provide its own assurances: Thousands of volunteers are receiving training in how to monitor ballot boxes, while lawyers are offering their services as on-site legal representatives in the event of polling station disputes. Amid excitement for real change and fear of worst-case scenarios, Turkish citizens are prepared for anything.

Alev Scott is the author of the book Turkish Awakening and a freelance writer based in Istanbul. Follow her on Twitter @AlevScott.